As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, PILOT NOTICED ENG TO BE RUNNING ROUGH, PILOT ELECTED TO RETURN TO POINT OF DEPARTURE FOR EVALUATION. INSPECTED MAGNETO TIMING & ADJUSTED. TIGHTENED NR FIVE CYLINDER INTAKE TUBE CLAMP & INSPECTED FUEL CONTROL FILTER SCREEN, NO DEFECTS NOTED. POST MX FLIGHT CHECK WAS SUCCESSFUL WITH NO DEFECTS NOTED. ACFT RETURNED TO SERVICE.